Synthesis of zeolite SSZ-16

ABSTRACT

A method is disclosed for synthesizing a zeolite having the framework structure of SSZ-16 using a structure directing agent comprising a dication selected from one or more of 1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpiperidinium]; 1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpiperidinium]; 1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpyrrolidinium]; and 1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpyrrolidinium].

TECHNICAL FIELD

This disclosure relates to the synthesis of zeolite SSZ-16.

BACKGROUND

Molecular sieve materials, both natural and synthetic, have beendemonstrated in the past to be useful as adsorbents and to havecatalytic properties for various types of organic conversion reactions.Certain molecular sieves, such as zeolites, aluminophosphates, andmesoporous materials, are ordered, porous crystalline materials having adefinite crystalline structure as determined by X-ray diffraction.Within the crystalline molecular sieve material there are a large numberof cavities which may be interconnected by a number of channels orpores. These cavities and pores are uniform in size within a specificmolecular sieve material. Because the dimensions of these pores are suchas to accept for adsorption molecules of certain dimensions whilerejecting those of larger dimensions, these materials have come to beknown as “molecular sieves” and are utilized in a variety of industrialprocesses.

Molecular sieves identified by the International Zeolite Association ashaving the framework type AFX are known. For example, the zeolite knownas SSZ-16 is a known crystalline AFX framework type material.

U.S. Pat. No. 4,508,837 discloses zeolite SSZ-16 and its synthesis inthe presence of a structure directing agent derived from1,4-di(1-azoniabicyclo[2.2.2]octane) lower alkane compounds.

U.S. Pat. No. 5,194,235 discloses the synthesis of zeolite SSZ-16 in thepresence of DABCO-C_(n)-diquat cations, where DABCO represents1,4-diazabicyclo[2.2.2]octane and n is 3, 4 or 5.

R. H. Archer et al. (Micropor. Mesopor. Mater. 2010, 130, 255-265)disclose the synthesis of an aluminosilicate AFX framework type zeoliteusing 1,3-bis(1-adamantyl)imidazolium cations as a structure directingagent.

The commercial development of SSZ-16 has been hindered by the high costof these structure directing agents and hence there has been significantinterest in finding alternative, less expensive structure directingagents for the synthesis of SSZ-16.

According to the present disclosure, it has now been found that theorganic dications described herein are effective as structure directingagents in the synthesis of SSZ-16.

SUMMARY

In one aspect, there is provided a method of synthesizing a zeolitehaving the framework structure of SSZ-16, the method comprising: (a)preparing a reaction mixture comprising: (1) a source of silicon oxide;(2) a source of aluminum oxide; (3) a source of a Group 1 or 2 metal;(4) a structure directing agent comprising a dication selected from oneor more of 1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpiperidinium];1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpiperidinium];1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpyrrolidinium]; and1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpyrrolidinium]; (5)hydroxide ions; and (6) water; and (b) subjecting the reaction mixtureto crystallization conditions sufficient to form crystals of thezeolite.

In another aspect, there is provided a zeolite having the frameworkstructure of SSZ-16 and comprising in its pores a dication selected fromone or more of1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpiperidinium];1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpiperidinium];1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpyrrolidinium]; and1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpyrrolidinium].

In yet another aspect, there is provided an organic nitrogen-containingcompound comprising a dication selected from one of the followingstructures:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a powder X-ray diffraction (XRD) pattern of the as-synthesizedzeolite prepared in Example 5.

FIG. 2 is a Scanning Electron Micrograph (SEM) image of theas-synthesized zeolite prepared in Example 5.

FIG. 3 is a powder XRD pattern of the calcined zeolite prepared inExample 6.

DETAILED DESCRIPTION Introduction

The term “as-synthesized” is employed herein to refer to a zeolite inits form after crystallization, prior to removal of the structuredirecting agent.

The term “anhydrous” is employed herein to refer to a zeolitesubstantially devoid of both physically adsorbed and chemically adsorbedwater.

As used herein, the numbering scheme for the Periodic Table Groups is asdisclosed in Chem. Eng. News 1985, 63(5), 26-27.

Reaction Mixture

In general, the present zeolite is synthesized by: (a) preparing areaction mixture comprising (1) a source of silicon oxide; (2) a sourceof aluminum oxide; (3) a source of a Group 1 or 2 metal (M); (4) astructure directing agent (Q) comprising a dication selected from one ormore of 1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpiperidinium];1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpiperidinium];1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpyrrolidinium]; and1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpyrrolidinium]; (5)hydroxide ions; and (6) water; and (b) subjecting the reaction mixtureto crystallization conditions sufficient to form crystals of thezeolite.

The composition of the reaction mixture from which the zeolite isformed, in terms of molar ratios, is identified in Table 1 below:

TABLE 1 Reactants Useful Exemplary SiO₂/Al₂O₃ 5 to 100 10 to 50 M/SiO₂0.10 to 1.00 0.10 to 0.70 Q/SiO₂ 0.05 to 0.50 0.10 to 0.30 OH/SiO₂ 0.10to 1.00 0.20 to 0.70 H₂O/SiO₂ 15 to 60 20 to 40wherein compositional variables M and Q are as described herein above.

Suitable sources of silicon oxide include fumed silica, colloidalsilica, precipitated silica, alkali metal silicates, and tetraalkylorthosilicates.

Suitable sources of aluminum oxide include hydrated alumina andwater-soluble aluminum salts (e.g., aluminum nitrate).

Combined sources of silicon oxide and aluminum oxide can additionally oralternatively be used and include colloidal aluminosilicates,aluminosilicate zeolites (e.g., zeolite Y) and clays or treated clays(e.g., metakaolin).

Examples of suitable Group 1 or Group 2 metals (M) include sodium,potassium and calcium, with sodium being preferred. The metal (M) ispreferably present in the reaction mixture as the hydroxide.

The structure directing agent (Q) comprises a dication selected from oneor more of 1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpiperidinium];1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpiperidinium];1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpyrrolidinium]; and1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpyrrolidinium]. Thedications are represented by structures (1), (2), (3), and (4) below:

1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpiperidinium]

1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpiperidinium]

1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpyrrolidinium]

1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpyrrolidinium]

Suitable sources of Q are the hydroxides, chlorides, bromides, and/orsalts of the relevant diquaternary ammonium compounds.

The reaction mixture may also contain seeds of a molecular sievematerial, such as SSZ-16 from a previous synthesis, desirably in anamount of from 0.01 to 10,000 ppm by weight (e.g., from 100 to 5000 ppmby weight) of the reaction mixture.

The reaction mixture can be prepared either batch wise or continuously.Crystal size, morphology and crystallization time of the zeolitedescribed herein can vary with the nature of the reaction mixture andthe crystallization conditions.

Crystallization and Post-Synthesis Treatment

Crystallization of the present zeolite from the above reaction mixturecan be carried out under either static, tumbled or stirred conditions ina suitable reactor vessel, such as for example polypropylene jars orTeflon-lined or stainless steel autoclaves, at a temperature of from125° C. to 200° C. (e.g., from 130° C. to 175° C.) for a time sufficientfor crystallization to occur at the temperature used, e.g., from 1 dayto 28 days. Crystallization is usually carried out in a closed systemunder autogenous pressure.

Once the zeolite crystals have formed, the solid product is recoveredfrom the reaction mixture by standard mechanical separation techniquessuch as centrifugation or filtration. The recovered crystals arewater-washed and then dried to obtain the as-synthesized zeolitecrystals. The drying step is typically performed at a temperature ofless than 200° C.

As a result of the crystallization process, the recovered crystallinezeolite product contains within its pore structure at least a portion ofthe structure directing agent used in the synthesis.

The as-synthesized zeolite may be subjected to treatment to remove partor all of the organic structure directing agent used in its synthesis.This is conveniently effected by thermal treatment in which theas-synthesized material is heated at a temperature of at least about370° C. for at least 1 minute and generally not longer than 20 hours.The thermal treatment can be performed at a temperature up to 925° C.While sub-atmospheric pressure can be employed for the thermaltreatment, atmospheric pressure is desired for reasons of convenience.Additionally or alternatively, the organic structure directing agent canbe removed by treatment with ozone (see, e.g., A. N. Parikh et al.,Micropor. Mesopor. Mater. 2004, 76, 17-22).

To the extent desired, the original Group 1 or 2 metal cations in thezeolite can be replaced in accordance with techniques well known in theart by ion exchange with other cations. Preferred replacing cationsinclude metal ions (e.g., rare earth metals and metals of Groups 2 to 15of the Periodic Table), hydrogen ions, hydrogen precursor ions (e.g.,ammonium ions), and combinations thereof.

The present zeolite can be formulated with into a catalyst compositionby combination with other materials, such as binders and/or matrixmaterials, which provide additional hardness or catalytic activity tothe finished catalyst. When blended with such components, the relativeproportions of SSZ-16 and matrix may vary widely with the SSZ-16 contentranging from 1 to 90 wt. % (e.g., from 2 to 80 wt. %) of the composite.

Characterization of the Zeolite

In its as-synthesized and anhydrous form, the present zeolite has achemical composition, in terms of molar ratios, as described in Table 2below:

TABLE 2 Useful Exemplary SiO₂/Al₂O₃ 5 to 50 5 to 25 Q/SiO₂ >0 to 0.2 >0to 0.1 M/SiO₂ >0 to 0.2 >0 to 0.1wherein Q comprises a dication selected from one or more of1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpiperidinium];1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpiperidinium];1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpyrrolidinium]; and1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpyrrolidinium]; and M is aGroup 1 or 2 metal.

It should be noted that the as-synthesized form of the present zeolitemay have molar ratios different from the molar ratios of reactants ofthe reaction mixture used to prepare the as-synthesized form. Thisresult may occur due to incomplete incorporation of 100% of thereactants of the reaction mixture into the crystals formed (from thereaction mixture).

As taught by U.S. Pat. No. 4,508,837, zeolite SSZ-16 has a powder X-raydiffraction pattern which includes at least the characteristic peaks setforth in Table 3 below.

TABLE 3 2-Theta d-spacing (nm) Relative Intensity^((a)) 7.52 1.176 M8.72 1.014 VS 11.59 0.763 S 15.71 0.564 VS 17.48 0.507 VS 17.66 0.502 S20.46 0.434 VS 21.85 0.407 VS 27.68 0.322 VS 30.68 0.291 VS ^((a))Thepowder X-ray diffraction patterns provided are based on a relativeintensity scale in which the strongest line in the XRD pattern isassigned a value of 100: W = weak (>0 to ≦20); M = medium (>20 to ≦40);S = strong (>40 to ≦60); VS = very strong (>60 to ≦100).

The powder X-ray diffraction patterns presented herein were collected bystandard techniques. The radiation was CuK_(α) radiation. The peakheights and the positions, as a function of 2θ where θ is the Braggangle, were read from the relative intensities of the peaks (adjustingfor background), and d, the interplanar spacing corresponding to therecorded lines, can be calculated.

Minor variations in the diffraction pattern can result from variationsin the mole ratios of the framework species of the particular sample dueto changes in lattice constants. In addition, sufficiently smallcrystals will affect the shape and intensity of peaks, leading tosignificant peak broadening. Minor variations in the diffraction patterncan also result from variations in the organic compound used in thepreparation. Calcination can also cause minor shifts in the XRD pattern.Notwithstanding these minor perturbations, the basic crystal latticestructure remains unchanged.

EXAMPLES

The following illustrative examples are intended to be non-limiting.

Example 1 Synthesis of1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpiperidinium hydroxide]

A 2-liter three-neck reaction flask equipped with an overhead stirrer, areflux condenser, and a heating mantle was charged with dichloromethane(800 mL), cyclohexane-1,4-dicarboxylic acid (100 g, 0.58 moles) andthionyl chloride (185 g). A trap containing water was connected to thereaction vessel through the top of the condenser to trap the producedHCl and SO₂ gases. The solution was heated at reflux for 4 hours andthen left to stir at room temperature overnight or until bubbleformation in the water trap ceased. The reaction mixture was thenconcentrated on a rotary evaporator at reduced pressure in hot waterbath to give cyclohexane-1,4-dicarbonyl dichloride (120 g, 98% yield) asa slightly orange oil.

A three-neck 2-liter reaction flask equipped with an overhead stirrer, areflux condenser, and an addition funnel was charged with cyclohexane(600 mL), triethylamine (75 g, 0.74 moles), and piperidine (48 g, 0.56moles). The mixture was cooled to 0° C. (water-ice bath) and a solutionof cyclohexane-1,4-dicarbonyl dichloride (60 g, 0.29 moles) incyclohexane (50 mL) was added dropwise via the addition funnel. Once allthe dichloride was added, the ice bath was replaced with a heatingmantle and the reaction mixture was heated at reflux overnight. Theresulting off-white solution (solids and solution) was cooled down toroom temperature and water was added dropwise until all the solidsdissolved. The resulting biphasic solution was transferred to aseparatory funnel and the two phases were separated. The organic phasewas diluted with ethyl acetate (250 mL) and washed with water (3×250 mL)and brine (300 mL). The aqueous layer was extracted with dichloromethane(2×150 mL). The dichloromethane extracts were added to the organicextracts and the combined organic extracts were dried over anhydrousmagnesium sulfate, filtered and concentrated on a rotary evaporator togive the desired diamide,1,1′-(1,4-cyclohexanediyldicarbonyl)dipiperidine, as light tan-coloredsolid in 94% (83.5 g) yield. The product was confirmed by NMR and IRspectroscopy.

A three-neck 2-liter reaction flask equipped with an overhead stirrer, areflux condenser was charged with anhydrous tetrahydrofuran (450 mL) andlithium aluminum hydride (29 g, 0.77 moles). The suspension was cooleddown to 0° C. by means of an ice bath. Then, a solution of1,1′-(1,4-cyclohexanediyldicarbonyl) dipiperidine (58 g) intetrahydrofuran (100 mL) was added dropwise via a dropping funnel whilestirring. Once all the diamide was added, the reaction mixture wasallowed to gradually warm up to room temperature and then heated atreflux overnight. The reaction was worked up by cooling it down to 0° C.by means of a water-ice bath and diluting the mixture withtetrahydrofuran (200 mL). Then, an aqueous NaOH solution (15 wt. %, 200mL) was added dropwise with vigorous stirring while keeping the reactionmixture temperature between 0° C. and 10° C. Once the addition of theNaOH solution was complete, water (20 mL) was added and the mixture wasleft to stir until the gray solution became a clear liquid and a whiteprecipitate. The reaction mixture was filtered through a fritted glassfunnel. The filtrate was dried over anhydrous magnesium sulfate,filtered and concentrated on a rotary evaporator at 15 torr and 75° C.to give 1,1′-(1,4-cyclohexylenedimethylene) dipiperidine (48.9 g, 94%yield) as yellow oil. The product was confirmed by NMR and IRspectroscopy.

In a 250 mL round bottom reaction flask,1,1′-(1,4-cyclohexylenedimethylene)dipiperidine (30 g, 0.104 moles) wasdissolved in methanol (250 mL). To this solution, iodomethane (46.6 g,0.32 moles) was added and the mixture was allowed to stir for 48 hours.Additional iodomethane (8 g) was added and the reaction mixture washeated at reflux for several hours. NMR analysis showed the reaction wascomplete. The reaction mixture was concentrated on a rotary evaporatorat reduced pressure and 70° C. to remove the solvent and the excessiodomethane. The obtained product, a dark tan solid, was purified byboiling in isopropyl alcohol (100 mL) to give brownish liquid and lighttan solids. The mixture was left to cool down to room temperature andthen diethyl ether (200 mL) was added to crystallize any dissolvedproduct. The mixture was filtered and the solids were dried on a rotaryevaporator at 26 torr and 75° C. The reaction afforded1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpiperidinium iodide](53.6 g, 89.3% yield) as an off-white solid.

The resulting diiodide salt was exchanged to the correspondingdihydroxide derivative by stirring it with OH-ion exchange resin(BIO-RAD® AH1-X8) in deionized water overnight. The solution wasfiltered and the filtrate was analyzed for hydroxide concentration bytitration on a small sample. The exchange afforded1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpiperidinium hydroxide]as a 0.65 molar solution (97% yield).

Example 2 Synthesis of1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpiperidinium hydroxide]

In a 250 mL round bottom reaction flask,1,1′-(1,4-cyclohexylenedimethylene)dipiperidine (25 g, 0.09 moles),synthesized as described in Example 1, was dissolved in methanol (150mL). To this solution, iodoethane (56 g, 0.36 moles) was added and themixture was allowed to stir for 72 hours. Then, additional iodoethane(10 g) was added and the reaction was heated at reflux for 8 hours. Thereaction mixture was then allowed to continue stirring overnight. NMRanalysis showed the reaction was complete. The reaction mixture wasconcentrated on a rotary evaporator at reduced pressure and 70° C. toremove the solvent and the excess iodomethane. The obtained product,dark tan solids, was purified by boiling in isopropyl alcohol (100 mL)to give brownish liquid and light tan solids. The mixture was left tocool down to room temperature and then diethyl ether (200 mL) was addedto crystallize any dissolved product. The mixture was filtered and thesolids were dried on a rotary evaporator at 26 torr and 75° C. Thereaction afforded1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpiperidinium iodide] (49.3g, 92.8% yield) as a light yellow solid.

The resulting diiodide salt was exchanged to the correspondingdihydroxide derivative by stirring it with OH-ion exchange resin (185 g,BIO-RAD® AH1-X8) in deionized water (150 mL) overnight. The solution wasfiltered and the filtrate was analyzed for hydroxide concentration bytitration on a small sample. The exchange afforded the desired1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpiperidinium hydroxide] in98% yield as a 0.65 molar solution.

Example 3 Synthesis of1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpyrrolidinium hydroxide]

The 1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpyrrolidiniumhydroxide] was prepared in a similar fashion to the procedure describedin Example 1 with the exception of using pyrrolidine in place ofpiperidine. The resulting aqueous1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpyrrolidinium hydroxide]solution had a concentration of 0.63 M.

Example 4 Synthesis of1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpyrrolidinium hydroxide]

The 1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpyrrolidiniumhydroxide] was prepared in a similar fashion to the procedure describedin Example 2 with the exception of using pyrrolidine in place ofpiperidine.

Example 5 Synthesis of aluminosilicate SSZ-16 (Al-SSZ-16) with1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpiperidinium hydroxide]

In a 23 mL Teflon liner, 3.1 g of a 0.65M solution of1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpiperidinium hydroxide]solution, 0.2 g of a 1N aqueous NaOH solution, 0.25 g of Na—Y zeolite,2.5 g of sodium silicate solution, and 3 g of deionized water were mixedthoroughly until a homogenous mixture was obtained. The Teflon liner wascapped and sealed in a Parr autoclave. The autoclave was affixed on arotating spit (43 rpm) in a heated oven at 150° C. The autoclave washeated for 6 days. Scanning Electron Microscopy indicated reactioncompletion by full crystallinity of the products. The reaction mixture(with a clear liquid layer and settled fine powdery material and a pHof >12.0-12.8) was filtered. The obtained fine solids were thoroughlyrinsed with water. The products were left to dry in open air overnightand then dried in a heated oven at 125° C. for 1 hour. The reactionafforded 0.53 g of pure crystalline SSZ-16 zeolite as indicated SEM andpowder XRD analysis.

The powder XRD pattern and SEM image of the resulting as-synthesizedzeolite product are shown in FIG. 1 and FIG. 2, respectively. The linesof the X-ray diffraction pattern of the as-synthesized zeolite productare given in Table 4.

TABLE 4 2-Theta d-spacing (nm) Relative Intensity^((a)) 6.16 1.434 M7.32 1.207 M 8.34 1.059 M 16.71 0.530 W 17.20 0.515 W 18.24 0.486 W18.52 0.479 W 20.88 0.425 VS 21.40 0.415 W 22.12 0.402 W 22.56 0.394 S24.81 0.359 W 25.44 0.350 M 27.27 0.327 W 27.66 0.322 W 29.64 0.301 W35.80 0.251 W ^((a))The powder X-ray diffraction patterns provided arebased on a relative intensity scale in which the strongest line in theXRD pattern is assigned a value of 100: W = weak (>0 to ≦20); M = medium(>20 to ≦40); S = strong (>40 to ≦60); VS = very strong (>60 to ≦100).

Example 6 Calcination of Al-SSZ-16

The as-synthesized product from Example 5 was calcined in air in amuffle furnace from room temperature to 120° C. at a rate of 1°C./minute and held at 120° C. for 2 hours. The temperature was thenramped up to 540° C. at a rate of 1° C./minute and held at 540° C. for 5hours. The temperature was then increased at the same rate (1° C./min)to 595° C. at held at 595° C. for 5 hours. There was a weight loss of17% which is typical for the loss of the structure directing agent fromcavities and pores of SSZ-16.

The powder XRD pattern of the calcined zeolite is shown in FIG. 3 andindicates that the material remains stable after removal of thestructure directing agent. The lines of the X-ray diffraction pattern ofthe calcined zeolite product are given in Table 5.

TABLE 5 2-Theta d-spacing (nm) Relative Intensity^((a)) 7.49 1.180 W8.73 1.012 VS 11.69 0.756 VS 12.98 0.682 VS 14.96 0.592 W 15.65 0.566 M17.50 0.507 M 18.00 0.493 S 19.88 0.446 M 20.38 0.435 VS 21.84 0.407 VS22.32 0.398 W 23.79 0.374 M 25.75 0.346 W 26.13 0.341 M 26.38 0.338 W27.56 0.323 M 28.19 0.316 S 30.24 0.295 M 30.57 0.292 S 31.16 0.287 W31.91 0.280 W 33.87 0.264 M 34.27 0.261 W 34.76 0.258 W ^((a))The powderX-ray diffraction patterns provided are based on a relative intensityscale in which the strongest line in the XRD pattern is assigned a valueof 100: W = weak (>0 to ≦20); M = medium (>20 to ≦40); S = strong (>40to ≦60); VS = very strong (>60 to ≦100).

Example 7

Example 5 was repeated except that 3.4 g of the structure directingagent was used and no NaOH was added. The reaction afforded 0.54 g ofSSZ-16 after 6 days of heating.

Example 8 Synthesis of Al-SSZ-16 with1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpiperidinium hydroxide]

Example 4 was repeated but the SDA was replaced with 3.2 g of a 0.65Msolution of 1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpiperidiniumhydroxide]. After 6 days of heating, the synthesis afforded 0.55 g ofSSZ-16 (0.55 g) with a trace amount of mordenite (MOR) impurity.

Example 9 Synthesis of Al-SSZ-16 with colloidal aluminosilicate and1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpiperidinium hydroxide]

In a 23 mL Teflon liner, 3.1 g of a 0.65M solution of1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpiperidinium hydroxide],3 g of a 1N aqueous KOH solution, and 5.25 g of a colloidalaluminosilicate (TX-15595, provided by Nalco Company) were mixedthoroughly until a homogenous mixture was obtained. The Teflon liner wascapped and sealed in a Parr autoclave. The autoclave was affixed on arotating spit (43 rpm) in a heated oven at 170° C. The autoclave washeated for 12 days. SEM indicated reaction completion by fullcrystallinity of the products. The reaction mixture, a paste at a pH of11.8, was filtered. The obtained fine solids were thoroughly rinsed withdeionized water. The products were left to dry in open air followed bydrying an oven at 125° C. for 1 hour. The reaction afforded 4.6 g ofpure crystalline SSZ-16 zeolite as indicated by SEM and powder XRDanalysis.

Example 10 Synthesis of Al-SSZ-16 with1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpyrrolidinium hydroxide]

In 23 mL Teflon liner, 3.2 g of 0.63M solution of a1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpyrrolidinium hydroxide],0.2 g of a 1N aqueous NaOH solution, 0.25 g of Na—Y zeolite, 2.5 g ofsodium silicate solution, and 2.9 g of deionized water were mixedthoroughly until a homogenous mixture was obtained. The Teflon liner wascapped and sealed in a Parr autoclave. The autoclave was affixed on arotating spit (43 rpm) in a heated oven at 150° C. The autoclave washeated for 6 days. Scanning Electron Microscopy indicated reactioncompletion by full crystallinity of the products. The reaction mixture(with a clear liquid layer and settled fine powdery material and a pHof >12.2-12.8) was filtered. The obtained fine solids were thoroughlyrinsed with water. The products were left to dry in open air overnightand then was dried in a heated oven at 125° C. for 1 hour. The reactionafforded 0.46 g of SSZ-16 and MOR (in about 40:60 ratio) as determinedby SEM and powder XRD analysis.

Example 11 Synthesis of Al-SSZ-16 with colloidal aluminosilicate and1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpyrrolidinium hydroxide]

In a 23 mL Teflon liner, 3.2 g of a 0.63M solution of1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpyrrolidinium hydroxide],3 g of a 1N aqueous KOH solution, and 5.25 g of a colloidalaluminosilicate (TX-15595, provided by Nalco Company) were mixedthoroughly until a homogenous mixture was obtained. The Teflon liner wascapped and sealed in a Parr autoclave. The autoclave was affixed on arotating spit (43 rpm) in a heated oven at 170° C. The autoclave washeated for 12 days. SEM indicated reaction completion by fullcrystallinity of the products. The reaction mixture, a paste at a pH of11.8, was filtered. The obtained fine solids were thoroughly rinsed withdeionized water. The products were left to dry in open air followed bydrying an oven at 125° C. for 1 hour.

The reaction afforded 0.5 g of SSZ-16 molecular sieve with a trace ofamount of mordenite (MOR) as indicated by SEM and powder XRD analysis.

Example 12 Synthesis of Al-SSZ-16 with colloidal aluminosilicate and1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpyrrolidinium hydroxide]

Example 10 was repeated except that1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpyrrolidinium hydroxide]was used as a structure directing agent.

Powder XRD showed the product to be a mixture of SSZ-16 and mordenite.

Example 13 Synthesis of Al-SSZ-16 with1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpiperidinium hydroxide]

A 23 mL Teflon liner was charged with 1.73 g of sodium silicatesolution, 0.13 g of a 1N NaOH solution, 0.18 g of CBV300 Y-zeolite(Zeolyst International; SiO₂/Al₂O₃ molar ratio=5.1), 2.14 g of a1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpiperidinium hydroxide]solution, and 1.33 g of deionized water. The composition of the reactionmixture, in terms of molar ratios, is reported in Table 6.

TABLE 6 SiO₂/Al₂O₃ 32.2 Na/SiO₂ 0.52 Q/SiO₂ 0.14 H₂O/SiO₂ 24.7

The Teflon liner was then capped and sealed within a steel Parrautoclave. The autoclave was placed on a spit within a convection ovenat 135° C. The autoclave was tumbled at 43 rpm for 5 days in the heatedoven. The autoclave was then removed and allowed to cool to roomtemperature. The solids were then recovered by filtration and washedthoroughly with deionized water. The solids were allowed to dry at roomtemperature.

The resulting zeolite product was identified by powder XRD as SSZ-16.

The product had a SiO₂/Al₂O₃ molar ratio of 12.5, as determined by ICPelemental analysis.

Example 14 Synthesis of Al-SSZ-16 with1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpiperidinium hydroxide]

A 23 mL Teflon liner was charged with 1.64 g of a sodium silicatesolution, 1.06 g of a 1N NaOH solution, 0.22 g of CBV300 Y-zeolite(Zeolyst International; SiO₂/Al₂O₃ molar ratio=5), 1.84 g of a1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpiperidinium hydroxide]solution, and 3.12 g of deionized water. The composition of the reactionmixture, in terms of molar ratios, is reported in Table 7.

TABLE 7 SiO₂/Al₂O₃ 25.4 Na/SiO₂ 0.59 Q/SiO₂ 0.12 H₂O/SiO₂ 37.9

The Teflon liner was then capped and sealed within a steel Parrautoclave. The autoclave was placed on a spit within a convection ovenat 135° C. The autoclave was tumbled at 43 rpm for 5 days in the heatedoven. The autoclave was then removed and allowed to cool to roomtemperature. The solids were then recovered by filtration and washedthoroughly with deionized water. The solids were allowed to dry at roomtemperature.

The resulting zeolite product was identified by powder XRD as SSZ-16.

Example 15 Synthesis of Al-SSZ-16 with1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpiperidinium hydroxide]

A 23 mL Teflon liner was charged with 1.56 g of a sodium silicatesolution, 0.83 g of a 1N NaOH solution, 0.27 g of CBV300 Y-zeolite(Zeolyst International; SiO₂/Al₂O₃ molar ratio=5.1), 1.64 g of a1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpiperidinium hydroxide]solution, and 0.16 g of deionized water. The composition of the reactionmixture, in terms of molar ratios, is reported in Table 8.

TABLE 8 SiO₂/Al₂O₃ 21 Na/SiO₂ 0.54 Q/SiO₂ 0.11 H₂O/SiO₂ 19

The Teflon liner was then capped and sealed within a steel Parrautoclave. The autoclave was placed on a spit within a convection ovenat 135° C. The autoclave was tumbled at 43 rpm for 5 days in the heatedoven. The autoclave was then removed and allowed to cool to roomtemperature. The solids were then recovered by filtration and washedthoroughly with deionized water. The solids were allowed to dry at roomtemperature.

The resulting zeolite product was identified by powder XRD as SSZ-16.

The product had a SiO₂/Al₂O₃ molar ratio of 10.5, as determined by ICPelemental analysis.

Example 16 Seeded Synthesis of Al-SSZ-16

Example 13 was repeated except that SSZ-16 seed crystals (18 mg) from aprevious synthesis were added to the reaction mixture. The resultingzeolite product was identified by powder XRD as SSZ-16.

Example 17 Seeded Synthesis of Al-SSZ-16

Example 14 was repeated except that SSZ-16 seed crystals (18 mg) from aprevious synthesis were added to the reaction mixture. The resultingzeolite product was identified by powder XRD as SSZ-16.

Example 18 Seeded Synthesis of Al-SSZ-16

Example 15 was repeated except that SSZ-16 seed crystals (18 mg) from aprevious synthesis were added to the reaction mixture. The resultingzeolite product was identified by powder XRD as SSZ-16.

The invention claimed is:
 1. A method of synthesizing a zeolite havingthe structure of SSZ-16, the method comprising: (a) preparing a reactionmixture comprising: (1) a source of silicon oxide; (2) a source ofaluminum oxide; (3) a source of a Group 1 or 2 metal (M); (4) astructure directing agent (Q) comprises a dication selected from one ormore of 1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpiperidinium];1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpiperidinium];1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpyrrolidinium]; and1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpyrrolidinium]; (5)hydroxide ions; and (6) water; and (b) subjecting the reaction mixtureto crystallization conditions sufficient to form crystals of thezeolite.
 2. The method of claim 1, wherein the reaction mixture has acomposition, in terms of molar ratios, as follows: SiO₂/Al₂O₃ 5 to 100M/SiO₂ 0.10 to 1.00 Q/SiO₂ 0.05 to 0.50 OH/SiO₂ 0.10 to 1.00 H₂O/SiO₂ 15to
 60.


3. The method of claim 1, wherein the reaction mixture has acomposition, in terms of molar ratios, as follows: SiO₂/Al₂O₃ 10 to 50M/SiO₂ 0.10 to 0.70 Q/SiO₂ 0.10 to 0.30 OH/SiO₂ 0.20 to 0.70 H₂O/SiO₂ 20to
 40.


4. The method of claim 1, wherein the crystallization conditions includea temperature of from 125° C. to 200° C.
 5. A zeolite having thestructure of SSZ-16 and comprising in its pores a dication selected fromone or more of:1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpiperidinium];1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpiperidinium];1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpyrrolidinium]; and1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpyrrolidinium].
 6. Thezeolite of claim 5, having, in its as-synthesized and anhydrous form, acomposition, in terms of molar ratios, as follows: SiO₂/Al₂O₃ 5 to 50Q/SiO₂ >0 to 0.2 M/SiO₂ >0 to 0.2

wherein: (a) Q comprises a dication selected from one or more of:1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpiperidinium];1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpiperidinium];1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpyrrolidinium]; and1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpyrrolidinium]; and (b) Mis a Group 1 or 2 metal.
 7. The zeolite of claim 5, having, in itsas-synthesized and anhydrous form, a composition, in terms of molarratios, as follows: SiO₂/Al₂O₃ 5 to 25 Q/SiO₂ >0 to 0.1 M/SiO₂ >0 to 0.1

wherein: (a) Q comprises a dication selected from one or more of:1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpiperidinium];1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpiperidinium];1,1′-(1,4-cyclohexylenedimethylene)bis[1-methylpyrrolidinium]; and1,1′-(1,4-cyclohexylenedimethylene)bis[1-ethylpyrrolidinium]; and (b) Mis a Group 1 or 2 metal.